This page describes the IBM SMS card "CR", and is part of the SMS card database.

Function of the card:
CTDL-One Way NPN No Loads Four on Card
Ctdl i way npn field replacement
U to T Converter (no loads)

Listed in 1401 SMS card usage

Complemented Transistor Diode Logic (CTDL) is IBM's term for a form of diode-transistor logic.

Part number: 371276

Field replacement part number: 370980

PCB number: 491443

Used in: IBM 1401, IBM 7070

Symbol:C

C: Converter. Used to translate from one voltage level to another, or to change the amplitude of the voltage swing about the same reference level.
IBM SMS card type CR 371276 IBM SMS card type CR 371276 IBM SMS card type CR 371276 IBM SMS card type CR 371276 IBM SMS card type CR 371276 IBM SMS card type CR 371276

Image courtesy of Henk Stegeman

References: IBM Standard Modular System, Component Circuits, p55
Coslet data
1_2 SMS Cards, pp36,111
This page created by Ken Shirriff on Wed Sep 15 18:15:10 2021.

The information on these pages comes from a variety of sources, especially old IBM documents on bitsavers.org, as well as information from the IBM 1401 restoration team, especially Tim Coslet's SMS data and Jim Hunt's data. Much of this information was obtained through OCR, so don't expect complete accuracy. These pages are not associated with IBM in any way.